Controlling traffic at an intersection, especially intersections having several movements of traffic therethrough, has been accomplished by different types of traffic control units. Basically, a traffic control unit allocates signal duration to various traffic movements in a selected sequence so that each movement can have access through the intersection. Ideally, access through the intersection by the several movements should be controlled in a manner to handle efficiently the traffic load at the intersection and prevent undue congestion. As illustrated in U.S. Pat. No. 3,886,496 traffic control units now use digital computers or other digital control devices. When using such digital controllers, it is still necessary to interconnect the controller with a monitor, load switches, and signal controlling devices. In addition, it is often necessary to provide a coordinator to tie intersection controllers with a master system. Such an arrangement is generally illustrated in U.S. Pat. No. 4,061,902. Irrespective of the components involved at the intersection, there is presented a substantial problem in the mechanical arrangement for interconnecting the various analog and digital components used to control the signalization at the intersection. The problem is the cost of actually interconnecting the components. These components are generally interconnected at the manufacturer's plant. This involves a substantial cost factor in the expense of the total traffic control unit. At one time, the various devices combined to form the traffic control unit were interconnected by cable harnesses which were installed prior to shipment for ultimate use at an intersection. These interconnecting harnesses did allow flexibility in changing the connections and in tying connections together for the purpose of changing the general function of the control unit at the intersection. However, this type of connecting arrangement was expensive. The cost did not justify the advantage of being able to change the hardwired interconnection between the devices subsequent to installation. To reduce the cost and be competitive in the marketplace, it has been suggested that various components be permanently wired together without any exposed terminals. Such a procedure did not allow for changing the hardwired interconnection between various terminals of the several devices comprising the total traffic control unit. Such a permanently wired device did reduce the cost of the unit; however, there was little versatility and a traffic engineer could not modify the operation of the unit to any substantial degree after it was installed at the intersection.